Why is this case new information? Provides a rare 5-year insight into peri-implantitis intrabony defect reconstruction, offering extended success and outcomes not frequently documented. Demonstrates the efficacy of aPDT with a 670-nm diode laser in achieving successful long-term outcomes, contributing valuable evidence to existing literature.Keys to successful management of this case: Success involves initial non-surgical debridement followed by a reconstructive strategy, incorporating guided bone regeneration and surface decontamination via aPDT. Long-term success hinges on patient compliance with routine oral hygiene, emphasizing the importance of adherence to preventive measures post-reconstruction to minimize recurrence risk.What are the primary limitations to success in this case? Variability in photosensitizer uptake, and potential risks such as tissue damage and bacterial resistance pose challenges to the effectiveness of aPDT. The existing literature on aPDT in peri-implantitis treatment lacks standardization in methodology, laser parameters, and follow-up durations, making it challenging to establish a universally accepted protocol.